In a test tube, fuse 0.25 g of the unknown with 1.5 g of powdered sodium hydroxide by heating with a bunsen burner. The escaping gas should be tested for the presence of ammonia or amines. Place moist pink litmus paper in the test tube, being careful to avoid touching the sides of the test tube with the paper. If ammonia or amine is being evolved, the litmus paper turns blue. After the tube has cooled, add just enough distilled water to dissolve the sample. The solution is then acidified with 2 M hydrochloric acid. A filter paper that has been covered with a paste of nickel(II) hydroxide is suspended over the test tube. The tube should be gently warmed to speed up the production of sulfur dioxide. If sulfur dioxide is present the green nickel(II) hydroxide is oxidized to grey-black nickel(IV) oxyhydrate.
Nickel(II) Hydroxide Reagent: The nickel(II) hydroxide reagent is prepared immediately before use by slowly adding 1 M sodium hydroxide to 0.20 g of nickel(II) chl0ride until no more solid precipitates. The precipitate is washed with 10-mL portions of cold water until the washings are no longer basic. The nickel(II) hydroxide is moistened with water and applied as a paste to a strip of filter paper.
A positive test for the presence of a sulfonamide is the evolution both of ammonia or amine and of sulfur dioxide.
None.
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